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SHELS: COMPLETE REDSHIFT SURVEYS OF TWO WIDELY SEPARATED FIELDS
Geller, Margaret J.,Hwang, Ho Seong,Dell’Antonio, Ian P.,Zahid, Harus Jabran,Kurtz, Michael J.,Fabricant, Daniel G. American Astronomical Society 2016 The Astrophysical journal, Supplement series Vol.224 No.1
<P>The Smithsonian Hectospec Lensing Survey (SHELS) is a complete redshift survey covering two well-separated fields (F1 and F2) of the Deep Lens Survey (DLS). Both fields are more than 94% complete to a Galactic extinction corrected R-0 = 20.2. Here, we describe the redshift survey of the F1 field centered at R.A.(2000) = 00(h)53(m)25(8).3 and decl.(2000) = 12 degrees 33'55'; like F2, the F1 field covers similar to 4 deg(2). The redshift survey of the F1 field includes 9426 new galaxy redshifts measured with Hectospec on the MMT (published here). As a guide to future uses of the combined survey, we compare the mass metallicity relation and the distributions of D(n)4000 as a function of stellar mass and redshift for the two fields. The mass-metallicity relations differ by an insignificant 1.6 sigma. For galaxies in the stellar mass range 10(10)-10(11) M-circle dot, the increase in the star-forming fraction with redshift is remarkably similar in the two fields. The seemingly surprising 31%-38% difference in the overall galaxy counts in F1 and F2 is probably consistent with the expected cosmic variance given the subtleties of the relative systematics in the two surveys. We also review the DLS cluster detections in the two fields: poorer photometric data for F1 precluded secure detection of the single massive cluster at z = 0.35 that we find in SHELS. Taken together, the two fields include 16,055 redshifts for galaxies with R-0 <= 20.2 and 20,754 redshifts for galaxies with R <= 20.6. These dense surveys in two well-separated fields provide a basis for future investigations of galaxy properties and large-scale structure.</P>
CATALOGS OF COMPACT GROUPS OF GALAXIES FROM THE ENHANCED SDSS DR12
Sohn, Jubee,Geller, Margaret J.,Hwang, Ho Seong,Zahid, H. Jabran,Lee, Myung Gyoon American Astronomical Society 2016 The Astrophysical journal Supplement series Vol.225 No.2
<P>We apply a friends-of-friends algorithm to an enhanced SDSS DR12 spectroscopic catalog, including redshift from the literature to construct a catalog of 1588 N >= 3 compact groups of galaxies containing 5178 member galaxies and covering the redshift range 0.01 < z < 0.19. This catalog contains 18 times as many systems and reaches 3 times the depth of the similar catalog of Barton et al. We construct catalogs from both magnitude-limited and volume-limited galaxy samples. Like Barton et al. we omit the frequently applied isolation criterion in the compact group selection algorithm. Thus the groups selected by fixed projected spatial and rest-frame line-of-sight velocity separation produce a catalog of groups with a redshift-independent median size. In contrast to previous catalogs, the enhanced SDSS DR12 catalog (including galaxies with r < 14.5) includes many systems with z less than or similar to 0.05. The volume-limited samples are unique to this study. The compact group candidates in these samples have a median stellar mass independent of redshift. Groups with velocity dispersion. less than or similar to 100 km s(-1) show abundant evidence for ongoing dynamical interactions among the members. The number density of the volume-limited catalogs agrees with previous catalogs at the lowest redshifts but decreases as the redshift increases. The SDSS fiber placement constraints limit the catalog's completeness. In spite of this issue, the volume-limited catalogs provide a promising basis for detailed spatially resolved probes of the impact of galaxy-galaxy interactions within similar dense systems over a broad redshift range.</P>
QUIESCENT COMPACT GALAXIES AT INTERMEDIATE REDSHIFT IN THE COSMOS FIELD. THE NUMBER DENSITY
Damjanov, Ivana,Geller, Margaret J.,Zahid, H. Jabran,Hwang, Ho Seong IOP Publishing 2015 The Astrophysical journal Vol.806 No.2
<P>We investigate the evolution of compact galaxy number density over the redshift range 0.2 < z < 0.8. Our sample consists of galaxies with secure spectroscopic redshifts observed in the COSMOS field. With the large uncertainties, the compact galaxy number density trend with redshift is consistent with a constant value over the interval 0.2 < z < 0.8. Our number density estimates are similar to the estimates at z > 1 for equivalently selected compact samples. Small variations in the abundance of the COSMOS compact sources as a function of redshift correspond to known structures in the field. The constancy of the compact galaxy number density is robust and insensitive to the compactness threshold or the stellar mass range (for M-* > 10(10) M-circle dot). To maintain constant number density any size growth of high-redshift compact systems with decreasing redshift must be balanced by a formation of quiescent compact systems at z < 1.</P>
HECTOMAP AND HORIZON RUN 4: DENSE STRUCTURES AND VOIDS IN THE REAL AND SIMULATED UNIVERSE
Hwang, Ho Seong,Geller, Margaret J.,Park, Changbom,Fabricant, Daniel G.,Kurtz, Michael J.,Rines, Kenneth J.,Kim, Juhan,Diaferio, Antonaldo,Zahid, H. Jabran,Berlind, Perry,Calkins, Michael,Tokarz, Susa American Astronomical Society 2016 The Astrophysical journal Vol.818 No.2
<P>HectoMAP is a dense redshift survey of red galaxies covering a 53 deg(2) strip of the northern sky. HectoMAP is 97% complete for galaxies with r < 20.5, (g-r) > 1.0, and (r -i) > 0.5. The survey enables tests of the physical properties of large-scale structure at intermediate redshift against cosmological models. We use the Horizon Run 4, one of the densest and largest cosmological simulations based on the standard. Cold Dark Matter (Lambda CDM) model, to compare the physical properties of observed large-scale structures with simulated ones in a volume-limited sample covering 8 x 10(6) h(-3) Mpc(3) in the redshift range 0.22 < z < 0.44. We apply the same criteria to the observations and simulations to identify over-and under-dense large-scale features of the galaxy distribution. The richness and size distributions of observed over-dense structures agree well with the simulated ones. Observations and simulations also agree for the volume and size distributions of under-dense structures, voids. The properties of the largest over-dense structure and the largest void in HectoMAP are well within the distributions for the largest structures drawn from 300 Horizon Run 4 mock surveys. Overall the size, richness and volume distributions of observed large-scale structures in the redshift range 0.22 < z < 0.44 are remarkably consistent with predictions of the standard Lambda CDM model.</P>
COMPACT GROUPS OF GALAXIES WITH COMPLETE SPECTROSCOPIC REDSHIFTS IN THE LOCAL UNIVERSE
손주비,황호성,Margaret J. Geller,Antonaldo Diaferio,Kenneth J. Rines,이명균,이광호 한국천문학회 2015 Journal of The Korean Astronomical Society Vol.48 No.6
Dynamical analysis of compact groups provides important tests of models of compact group formation and evolution. By compiling 2066 redshifts from FLWO/FAST, from the literature, and from SDSS DR12 in the fields of compact groups in McConnachie et al. (2009), we construct the largest sample of compact groups with complete spectroscopic redshifts in the redshift range 0.01 < z < 0.22. This large redshift sample shows that the interloper fraction in the McConnachie et al. (2009) compact group candidates is 42%. A secure sample of 332 compact groups includes 192 groups with four or more member galaxies and 140 groups with three members. The fraction of early-type galaxies in these compact groups is 62%, higher than for the original Hickson compact groups. The velocity dispersions of early- and late-type galaxies in compact groups change little with groupcentric radius; the radii sampled are less than 100 h−1 kpc, smaller than the radii typically sampled by members of massive clusters of galaxies. The physical properties of our sample compact groups include size, number density, velocity dispersion, and local environment; these properties slightly differ from those derived for the original Hickson compact groups and for the DPOSS II compact groups. Differences result from subtle differences in the way the group candidates were originally selected. The abundance of the compact groups changes little with redshift over the range covered by this sample. The approximate constancy of the abundance for this sample is a potential constraint on the evolution of compact groups on a few Gigayear timescale.